Combined bridge plug and drilable whipstock



April 28, 1942. J. M. CLARK -COMBINED BRIDGE PLUG AND DRILLABLEWHIPSTOCK Filed NOV. 7, 1940 lNVENTOk 23. 5%. 1. James M 6/0/16 5 ATIORY Fatente d Apr. 28, 1942 stares ZQMAM COMBINED BRIDGE PL US: ANDDRILL-ABLE WHIPSTOCK poration of Delawar Application November 7, 1940,Serial No. 364,667

1 Claim.

My invention relates to a combined bridge plug and drillable whipstock.

Trouble with crooked holes is almost an every= day occurrence withrotary drilling. I do not mean to imply that every rotary drillingoperation results in a crooked hole. Such trouble is encountered,however, in one hole out of twenty or thirty drilled by rotary drilling.This crooked hole trouble need not be serious, although it may beexpensive.

Sometimes it is desirable to drill a crooked hole purposely. A straighthole may be drilled to a water sand. The producing sand may be under ariver or other body of water through which a well cannot be drilled. Insuch case acrooked hole is purposely drilled in order to reach thedesired producing sand.

Controlled directional drilling is most frequently practiced with adeflecting tool known as a removale whipstock. The knuckle joint mayalso be used, but is employed less frequently.

Whipstocks known to the art consist of one piece including a chiselpoint to engage the bottom of the hole and prevent turning, a taperedconcavity to guide the bit into the wall and a ring on the top of thetool by means of which it may be withdrawn from the hole.

Many failures are had directional drilling operations. In the customarymode of procedure the old hole is plugged backand a whipstock set whichdeflectsthe drill bit in the desired direction. Many cement plugs failto set due to the large annular space between the drill pipe and thehole. This induces channeling and prevents sumcient scrubbing of thewalls. After obtaining a normal cement plug, sidetracking attemptsfrequently fail because the plug is still soft and more drillable thanthe formation surrounding it. Because of ,the softness of the cementplug when the bend in the sidetrack hole is reamed the cement plugisfrequently drilled into.

' One object of my invention is to provide a combined drillablewhipstock and cement plug which will make for greater certainty insidetracking operations.

Another object of my invention is to provide a combined bridge plug andwhipstock which may be set in the hole and need not be removed, savingthe necessity of removing the whipstock from the hole. 1

Other and further objects of my invention will appear from the followingdescription.

In the accompanying drawing which forms part of the instantspecification and is to be read with sidetracking or in .coniuinctiontherewith, and in which like reference numerals are 'used to indicatelike parts in the various views:

Fig. 1 is a diagrammatic view of a crooked hole showing a. combinedbridge plug and whipstock of my invention in use.

Fig. 2 is an enlarged sectional view of my combined bridge plug anddrillable whipstock.

Fig. 3 is a sectional view taken on the line 3-3, Fig. 2.

Fig. 4 is a sectional view taken on the line 4-4, Fig. 2.

Referring now to Fig. 1, it is desired to drill a hole 2 to a producingsand I. The hole deviated and the lower portion 3 of the hole missed theproducing sand I. A fish or bridge 4 was placed in the hole and thecombined bridge plug and whipstock 5 of my invention cemented on top ofthe fish 4. The whipstock then deflects the drill bit 6 along theproposed path indicated by the construction lines I.

The combined whipstock and bridge plug 5 is constructed of cement inwhich there is an aggregate of particles 8 of gravel, cast iron frag--ments, and the like to give suflicient hardness to the whipstock. A pipe9 of drillable material is embedded in the whipstock body 5,. andprovided at its upper portion with a left hand thread Hi. The lowerportion of the whipstock is provided with ducts H communicating with thepipe 3.

In operation, a bridge or lower portion 3 of the old hole, and thewhipstock supported on the bridge oriented in the desired direction. Thedrill bit is removed from the drill pipe I3 and the end of the drillpipe secured to the whipstock by means of the left handed thread it. Itis understood, of course,

that any suitable connecting means may be employed, suchas a J slotconnection or shear pin. The plug is lowered to the desired position bymeans of the drill pipe. After it is in the desired position, cement isrun through the drill pipe and the drillable pipe 9 in the whipstock,out of the ducts H into the hole above the fish i2. Cement It fills thehole around the whipstock, which acts as aplug in addition to performingthe duties of a whipstock.

It will be observed that the cementing operation will be more successfulbecause of the small annular space between the plug 5 and the walls ofthe hole 3. Due to the fact that the whipstock is made of hardermaterial than the surrounding formation, sidetracking operations will bemore successful. Furthermore, reaming of the hole at the point ofdeviation will likewise be fish I2 was set in the possibIe because ofthe hardness of the plug and whipstock.

If for any reason the plug sticks in the hole placed in the properposition, it could before it is without damage to be drilled with lightweight, the hole.

After the cement threaded from the left drill bit 6 again placed on thedrilling string. Drilling operations then proceed, the drill bit beingdeflected by the inclined deflecting surface 15 formed on the whipstock.

In a hole which has an internal diameter of 9% inches, for example, thewhipstock would be 20 feet long from tip to tip. The upper taperedsurface l5 would be 6 feet long. The lower tapered surface would be 1Vzfeet long. The main body of the whipstock would be 8 inches in diameterwhile the pipe 9 made of drillable alloy would be 2 inches in diameter.The diameter of the ducts ll would be 1 inch. It is understood, 01course, that any reasonable length may be run, and the above dimensionsare given by way of illustration and not by way of limitation.

has set the drill pipe is unhanded thread l0 and the ing in combinationa body member formed of concrete, said concrete comprising cement and anaggregate of hard material, a pipe formed of relatively soft drillablealloy fixedly embedded axially of said body member, aligning transverseducts formed in said body member and said pipe adjacent the lower end ofthe body. said pipe being formed adjacent its upper portion with a lefthand thread, said .body member provided with an inclined surface at itsupper end.

JAMES M. CLARK.

